Add water and mangoes to a saucepan. Heating over medium heat for about 6 minutes, stirring frequently until mangoes are soft. Remove from heat and let stand to cool.
Preheat oven to 325 degrees F and line a baking sheet with parchment paper. Set aside.
Combine flour, baking soda, baking powder and salt in a small bowl and mix well. Set aside.
Beat together butter and sugars until fluffy, about 6 minutes. Add eggs and vanilla and beat well until combined. Add in dry ingredients and beat just until combined. Fold in mangoes and nuts.
Using a 2 tablespoon portion scoop, scoop cookies onto a baking sheet, keeping them 2" apart.
Bake for 10-14 minutes or until centers are set and cookies are browned. Let stand for 2 minutes on the baking sheet before moving to a cooling rack to cool completely.